Stress-balancing splice bar



B. G. BRAINE sTaEss BALANGINGSPLIGE BAR 2 Shea s-Shee Filed Nov. 28. 1925 2 Sheets-Shwt 2 E. G. BAINE STRESS BALANCING SPLICE BAR Filed NOV. 28, '1925 Feb. 16 l, 26.,

Panarea ree. le, l ,573,476

BANCROFT G. BRAINE, OF NEW YRK, N. Y., ASSIGNOR TO THE RAIL JOINT COM- PANY, OF NEVI YORK, N. Y., A. CORPORATION OF NEW YORK.

STRESS-BALANCNG SPLICE BAR. Y y,

Application filed November 28, 1925. 361ml No. 71,895. la'

To all nolo/fa it muy concern.: splice bar planned and constructed accordlle it known that l', Bnncnorr (l. Bruine, ing to the present invention and shown` fit,- a citizen oi the ljnited residing al. tim;F the l'isbinf,r space of a rail. i New York, in the county of flew York. and Figure 2 is a similar View of the seme 5 State ot New York, have invented certain Splice bar illustrating the location of the e0 new und useful improvements in Stress centers of gravity of the head and foot porllulancing Splice Bars, of which the i'ollo\v tions ot' the bar respectively above and bea specification. louY a neutral axis or middle line; the een- This invention relates to a splice bar conter.. of gravity for the` full bar also being struction involving a novel distribution ol indicated. e5

metal whereby a substantial lightening ot Figure 3 is a similar view ot the same bar the bar may be obtained, and :it the same showing the location of the center lines of time the whole structure niaterially strcngthstress ot the head and foot portions of the cned as to its stress-resisting capacity and bar with reference to a neutral anis or l5 rendered more flexible, middle line. 70

To that end the invention primarily has Figure 4 is a similar View of the same bar in view a carrying forward, of the principles showing, by dotted lines, a form ot' splice of metal distribution underlyingr the invenbar heretofore used which has been replaced tion of inyformer Patent No. 1,546,883, by the improved bar shown in full sectiondated July 21,1925, wherein a foundation the two bars being.,r accurately superimposed 75 s laid .for producing a Splice hay balanced t0 lllullule the Substantial (lcpllule IOIU este vstresses by having zones of metal of thd dotted line shape. substantially the sanie area at substantially A primary feature of the invention of equal distances respectively above and he practical importance is that of producing a low an axis or lniddle line so that in an splice bar shape having a novel distribution 8 0 unsyrnnietrical shape, such as the modern ol metal particularly in the web and foot splice bar section, the portions of the splice members in their relation to an enlarged and hay regpgglwy abge@ mi below the no1-iwidened head, that Will provide a balancing zontal axis are of substantially equal area Gf the bar not only as to the areas respec- 39 and modulus. tively above and below a neutral axis or 85 Accordingly? it is the Purpose of the pregimiddle line, butalso statically balanced and ent invention to so shape the splice bar seo balanced as to stresses, thereby necessarily ltion in its head, web and foot member, and Involving a Substantial balancing of the to so relate the metal distribution in the plu/Sicili p'OpIeS O the eilccaivc unsymshape above and belen7 a neutral axis or metrical parts of the-bar respectively above 9o middle line, that the physical properties of and below the said neutral axis oruniddle the effective unsyminetrical parts of the bar line. Accordingly, in laying out a splice bar 4at the top and at the bottom will be almost, Shape following the principles of the presif not'quite, balanced, whereby the centers ent mvcntion to obtain a balancing of v40 of gravity and the centers of stresg of th@ stresses in' the statically balanced portions, '95

top and bottom parts of the bar 1will be so HS Well 21S t0 areas, the important factors to located that the bar Will not only be balbe calculated and employed are the moment anced as to area, but also statically balanced 0f inertia, the section modulus, the static and balanced as to stresses. 'With these and moment, as Well as the area. Furthermore, it other objects in view which will be apparent is important to the successful carrying out to those skilled in this art as the nature of of the invention that the center of gravity the invention 'is better understood, the same ol the head part of the bar shall be at subconsists in the novel features hereinafter stantially ythe same distance above the neumore fully described, illustrated and 'tral axis or middle line asthe center of claimed; and While the invention is susceptigravity for the foot member of the bar is ble of embodiment in various n'lodilications below the said axis or middle line, and that of ankparticular shape, a preferred and the center line of stress of the heed part of practical embodiu'ient thereof is shown in the bar shall Abe at substantially the .same the accompanying drawings, "i`1ru'l1ich distance abolie the. neutralaxis or//muldle .Figure l is 'a cross-sectional view of a line as thecenter hneostrese for the foot 110 part oft' the bar is below the said anis or middle line.

Certain definitions are important to bear in mind in obtaining a full understanding of the present. invention particularly as to the moment of inertia, the static moment, the section modulus and the determination ot the center line of stress. Accordingly, it is here notedv that the moment of inertia ot a particular area about any axis isthe sum of the product of the area multiplied by the square of the distance from the assumed axis of rotation tothe center of gravity ot' that u ea, plus the moment of inertia of that area about its neutral axis parallel to the assumed axis of rotation; while the static moment ol a particular' area the product of that area multiplied by the distance from an assumed axis of rotation to its neutral axis parallel to -called strain thev assumed axis of rotation.

The section modulus of a section is a coefficient or measure of a torce, and in dealing with metal shapes ot the splice bar type the section modulus tlnereol is in cll'cct. a modulus of rupture, that isfthe measure oit the force tending to make a fracture or rue ture and is directly related to the moment ot inertia.

The calculation for the section modulus` of a splice bar section is made according to the formula of dividing the moment et inertia by the distance from. the axes respectively to the extreme top and bottom libres ot the section, thus obtaining the top modulus o the section and the bottom modulus oi` the section. And, with reference to locating the center of stress of the upper and lower parte of the bar this phase ot the bar is directly related to both the moment ot inertia and the static moment, and the center of stress oil either of the Aportions above or below tbe neutral ,axis of the splice bar section is obtained by dividing the moment of inertia, ot the portion'being considered, by its static moment. Y

As the foregoing factors enter into tbe successful carrying out ot' the invention and invo'lve both the first and second moments of a bar, it is also important to note that in balancing the bar not only as to area but also as to stress there is taken into consideration the well known 'tact thattbe eliect of a load acting on any piece of construction is a change of form or dimension ofthe piece and this change et form or dimension is vand tbc combination of internal forces which are called into play in the section to resist or balance the load is called stress Therefore, in carrying out the invention to provide for a balancing of stresses at equal distances above and below a neutral anis or middle line the upper and lower sections ot thc bar'have effective zones of metal of the same or substantially the same arca, dcsign'atrd lJ 2 and 8 in the exisraele' ample given on Fie. fly of the drawings, at equal or substantially equal distance 'from a neutral axis or middle line designated in the drawings. namely,.`to provide the bar sections with zones of metal ot substantially the same area at equal distances from tbc axis or middle line it will be understood that this has particular reference to the i'msynunetrical parts ot the bar: because in a web ot uniform uidth at and adjacent the neutral axis thc areas ot the metal in the uniform part ot the web necessarily will have the same arca at equal distances above and below tbe axis. PBut, regardless of that distinction it is important in carrying out the invention that the substantiallv equal areas or zones ot metal at equal distances from the axis shall not only be otl substantially the same area and therefore balanced as to area, but also must be substantially balanced as to all ot their cll'ective physical properties, and furthermore, as to their centers of gravity and center lines of stress.

The 'feature of having the effective zones ot metal of substantially the same areain the unsymn'ictrical parts oi' the bar at equal distances respectively above and below the axis or middle line, coupled with a substantial luilancing of the effective pllysical properties of such zones of metal results in the desirable eiect of advantageously locating the centers of gravity for the upper and lower unslvinmetrical parts of tbe bar. This is shown in Fig. 2 of the drawings, which bearsthereon the calculations., for the bar illustrated, showing the center of gravity 'for the upper or head member ot the bar as being substantially the same distance above tbe iieutral axis as the distance of the center of; gravity for tbe lower or 'foot member of the bar below the neutral axis. The figures given indicate these distances to be substantially the same -within a very small traction. Likewise the novel distribution ot metal referred to permits ot locating the center lines of stress in the most effective locations and in practically balanced relation. .This is shown in Figfl of the drawings, wherein for the splice bar illustrated the centerl line of stress of the upper or head member of the bar is shown as 1.1% inches above tbe neutral axis and the lcenter line ofstvess for the lower or foot member of the bar as 1.72 inches below the neutral anis7 said distances being the same Within a very small traction.

lthas been pointed out that the invention contemplates balancing tlic physical.properties of the unsymuietrical zones oi' parts of the liar respectively above and below the axis or middle liuc llicrco'l and in order to malte clear that. phase of the invention reference is made to the example ot' the zoning of the areas of metal as shown in Fig'. 4 ot the drawings. As'illustrated in that figure of ln obtaining that 1'esult,'

lill) 1.57am@ ,Y

made to the physical properties ol zones .2-2. According' to the calculations made for these zones the physical properties of upper zone 2 are:

Area (A) .90; static moment 1.09;l

inertia (l) 1.34. i. The physical properties for lower zoney 2 are: l

Area .85; static moment 1.05; inertia The physical properties lor upper zone 3 are: 4

Area 1.83; stationnement 3.50; inertia The physical proyerties' for lower zone 3 arez' f Area' 1,85;

According to there calculations the total of the physical properties for the upper zones 2 and 3 are:

Y Area 2.73; static moment 41:59; ,inertia are, and the total ot the hyeical properties for the loafer zones an 3 are: i

Area. 2.70; static moment 4.61; inertia Thus, it will be se 'that Within en exceed'- ingly small freetime theeective unsymmetrical parte et the respectively above and below the neutral arie are substantially balanced as to their phyaieal nropertiea.

In order to ehm-ahora this balancing ct the physical properties ci' the bar above and below the nentral'anis carries out in the lull section there is shown in the drawings the calculations made for zones 1 and '2 in the straight web' ot the bar and when these are added to the totals above Given for the unsynnnetrical parte or the ar' the physical properties oi the Whole section above the horizontal neutral axis are:

Area 3.21; static moment 4.78; inertia 8.27, and the physical properties for the Whole section below the borizntal neutral anis are:

lstatic moment`3.56; inertia Area 3.18; static moment 4080; inertia 8.25. ln the lexamples given thev horizontal neutral axis has been calculated a trifle below the exact middle line of the section,

namely, at distances of 2.53 from the axis neutral anis to the entraine bottom fibres, and all calculations` given are approximately correct.

Figure fl of the drawings somewhat Visualizes themetal distribution claimed herein. lt shows by' dotted lines an old form oi splice bar designated by the reference letter 0 over which is accurately cigutieriin-4 posed the new type splice bar desi 'mated by there'lerence letter N, and in lull ines. By comparing these superimposed shapes N and 0 it will be eeen that the web 10 ot the bar has been materially thinned from its inner eide as indicated at 11 Without disturbing the distance of the outerside ot the bar from the rail web and in addition to this change in the web construction the metal in the inner part 12 ol the head 13 of the bar has been reduced in its Vertical depth as will be indicated by the metal removal designated b` the reference number l/l. lt will be seen tnat the metal removal 11 ia carried downwardly and inwardly past the web ofthe bar as shown. at 15 so as to include the inner foot projection 1, and a substantial body of metal deaignatcd by theepace 17 is eliminated from the upper aide of the foot mem ber andthe latter projected at its outer'eatremity as l@ greater distance beyond the toot llanero et the rail than the outward projection or: the thelr loot dang@ ot the old type bar 'heoe details in the metal distribution are made proportionately in order to obtain a. Shape wherein-the areas or zones ot metal shall be substantially the name at equal distances respectively above and below the axis or vmiddle line, and whereby the physical properties of said areas and zones ot metal will be substantiall or approximately the same, with the reso tof locating the centers oli gravity and the center linea ot etres's at advantagecu points in the baraao as to better resist the etrain and Streesto which the bar is subjected.

A turtbel feature ot practical importance in the present invention is the inertia-area ratio established and maintained lor the whole ecctidn as compared with the inertiaarea ratio established and maintained for the unsymxnetrical portions of the bar re- Spectively above and below its axis of rotation. The factor or economy in metal dis tribution of any section or a portion of a section is represented by the ratio of the moment ol inertia to the area, that is, ,O

or the inertia-area ratio, and. in developing the present invention 1t uae been found that a moet eilectiv-e and economical diatrilmtion of metal is obtained by making 'the inertia.- area ratio ci the whole section substantially equivalent with the average of the inertiaarea ratios for the unsymrnetrical parte ot .the bar respectively above and below. its axis of rotation. lo other Words the prefirent invention contemplates melting the in ertia-orea ratio o" the Whoie section sub# stantielly the seine for the top7 bottoni and f the full section,

-While the essentials of the invention are 'best demonstretecl by using the horizontal neutral axis as a basis -for the calculations it is to be unflerstooti` that l d'0 not limit my invention to the use of Such exis for that purpose, because seine other assumed axis of rotation may be employed to determine the novel distribution of metal claimed herein without departing from the principles or sacrificing any of the advantages of the invention.

ldistances respectively above and below a 'neutral axis, the splice bar section having a Liroportlonal distribution ot metal to dispose the center of gravity of the head member at the same distance above the axis as the distance below the afis of the center of gravity of the foot member and also to dispose the Center line ot stress or' the head member at substantially the same distance twente above the axis :is the distance beiow'the exis ofthe center line of stress ofthe toot memher y f 3. A splice bei' section having a proportional reducementwin metal at the inner .eide of the web, the underside of the inner head 'projection and the upper side of the foot ange to provide Lzones of metal of substam tially the same area and physical properties at equal distances respectively above and below the neutral axis.

4. A splice her section having a proportional redueen'ient in metal atthe inner side of the web, the under sido of the inner head projection and the upper side of the foot fiange projected beyond the vertical plane of the outer tace ofithe bar a dis tance substantially equal tothe height of said vertical tace; said distribution of metal providing zones of vmetal' or' substantially the same area and physical properties at equal distances respectively above and below the neutral axis.

5. A splice bar having a proportional distribution of metal in its upper and lower unsymmetricel portions to provide a, substantial equivalence between the ratios represented by the moment ot interi@J of the Whole section divided by its area enel the ratios represented by the mornent'o inertia, of vthe unsymmetricel portion above its exis of rotation divided by its reo and themoment of intertia of the unsymmetrcal portion below said axis divideti oy its aree.

In testimony whereof l hereunto ax my signature.

BANCRFT G. BRMNE.' 

